Rather than offend homosexuals by directly confronting the issue of their sinful lifestyle, modern evangelism often tries to soften the approach by saying that,
“God hates the sin, but loves the sinner.”
This isn’t a new concept.
Charles Finney stated,
“God is not angry merely against the sin abstracted from the sinner, but against the sinner himself. Some persons have labored hard to set up this ridiculous and absurd abstraction, and would try to make it appear that God is angry at sin, and not at the sinner. Now this is supreme nonsense. The sin has no moral character apart from the sinner. The act is nothing apart from the actor. The very thing that God hates and disapproves is not the mere event—the thing done in distinction from the doer; but it is the doer himself. It grieves and displeases God, that a rational moral agent, under His government, should array himself against his own God and Father, against all that is right and just in the universe. This is the thing that offends God. The sinner himself is the direct and the only object of his anger.”
So the Bible shows. God is angry with the wicked [Psalm 7:11], not with the abstract sin. If the wicked turn not, God will whet His sword—He has bent His bow and made it ready—not to shoot at the sin, but the sinner—the wicked man who has done the abominable thing. This is the only doctrine of either the Bible or of common sense on this subject” (The Guilt of Sin by Charles Finney ).
The biblical way to witness to a homosexual is not to argue with him about his lifestyle but to use the Law to bring the knowledge of sin.
Psalm 19:7 KJV
The law of the Lord is perfect, converting the soul: the testimony of the Lord is sure, making wise the simple.
Romans 7:7 KJV
What shall we say then? Is the law sin? God forbid. Nay, I had not known sin, but by the law: for I had not known lust, except the law had said, Thou shalt not covet.
1 Timothy 1:8-11 NKJV
But we know that the law is good if one uses it lawfully,  knowing this: that the law is not made for a righteous person, but for the lawless and insubordinate, for the ungodly and for sinners, for the unholy and profane, for murderers of fathers and murderers of mothers, for manslayers,  for fornicators, for sodomites, for kidnappers, for liars, for perjurers, and if there is any other thing that is contrary to sound doctrine,  according to the glorious gospel of the blessed God which was committed to my trust.
Romans 3:20 KJV
Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.
Galatians 3:23-25 KJV
But before faith came, we were kept under the law, shut up unto the faith which should afterwards be revealed.  Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith.  But after that faith is come, we are no longer under a schoolmaster.
This will show a homosexual that he is guilty of breaking God’s Holy Law, and he is damned not because of, but despite his sexual preference. The Law was made for homosexuals, as well as other lawbreakers.
Psa 5:4,5 KJV For thou art not a God that hath pleasure in wickedness: neither shall evil dwell with thee.
Psa 5:5 KJV The foolish shall not stand in thy sight: thou hatest all workers of iniquity.
2 Peter 2:6-8 KJV And turning the cities of Sodom and Gomorrha into ashes condemned them with an overthrow, making them an ensample unto those that after should live ungodly;
2 Peter 2:7 KJV And delivered just Lot, vexed with the filthy conversation of the wicked:
2 Peter 2:8 KJV (For that righteous man dwelling among them, in seeing and hearing, vexed his righteous soul from day to day with their unlawful deeds;)
2 Peter 2:9-22 KJV
The Lord knoweth how to deliver the godly out of temptations, and to reserve the unjust unto the day of judgment to be punished:  But chiefly them that walk after the flesh in the lust of uncleanness, and despise government. Presumptuous are they , selfwilled, they are not afraid to speak evil of dignities.  Whereas angels, which are greater in power and might, bring not railing accusation against them before the Lord.  But these, as natural brute beasts, made to be taken and destroyed, speak evil of the things that they understand not; and shall utterly perish in their own corruption;  And shall receive the reward of unrighteousness, as they that count it pleasure to riot in the day time. Spots they are and blemishes, sporting themselves with their own deceivings while they feast with you;  Having eyes full of adultery, and that cannot cease from sin; beguiling unstable souls: an heart they have exercised with covetous practices; cursed children:  Which have forsaken the right way, and are gone astray, following the way of Balaam the son of Bosor, who loved the wages of unrighteousness;  But was rebuked for his iniquity: the dumb ass speaking with man’s voice forbad the madness of the prophet.  These are wells without water, clouds that are carried with a tempest; to whom the mist of darkness is reserved for ever.  For when they speak great swelling words of vanity, they allure through the lusts of the flesh, through much wantonness, those that were clean escaped from them who live in error.  While they promise them liberty, they themselves are the servants of corruption: for of whom a man is overcome, of the same is he brought in bondage.  For if after they have escaped the pollutions of the world through the knowledge of the Lord and Saviour Jesus Christ, they are again entangled therein, and overcome, the latter end is worse with them than the beginning.
 For it had been better for them not to have known the way of righteousness, than, after they have known it , to turn from the holy commandment delivered unto them.  But it is happened unto them according to the true proverb, The dog is turned to his own vomit again; and the sow that was washed to her wallowing in the mire.
Zephaniah 3:5 KJV
The just Lord is in the midst thereof; he will not do iniquity: every morning doth he bring his judgment to light, he faileth not; but the unjust knoweth no shame.